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Old 6th Oct 2017, 20:08   #81 (permalink)
 
Join Date: Jul 2011
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Originally Posted by SplineDrive View Post
I haven't been able to find rotor diameter data for the SB>1, but have zero doubt both JMR demonstrators are larger in gross weight and planform than the H-60 and AH-64 aircraft.
I hope they are ready for some downwash with these small diameter props....
I can see this work as a strategic/ slight tactical transport, however how it should replace the Blackhawk and Apache in the real tactical role, requiring very low level manoevering, quick stops, fast insertions and extractions..... well let's just say I am curious how it performs in this part of the flight envelope.... that it can fly far and fast is nice, but is only a part of the required performance I guess.
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Old 8th Oct 2017, 02:23   #82 (permalink)
 
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Originally Posted by CTR View Post
I concur. My friends from the 609 program are the same engineers that oversaw the V-280 system installations, and they followed the same bird strike survivability design requirements as for an FAA certified aircraft.
Good point about the AW609. Looking at the picture below shows that area of the AW609 to be fairly well protected from impacts with the nacelle tilted vertical.

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Old 9th Oct 2017, 01:59   #83 (permalink)
 
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Originally Posted by NWSRG View Post
Maybe this is a slightly naive suggestion...

...but would buying both not be the best option for the US Army? Common engines (I think?), potentially commonality in avionics, but different platforms for different missions. Not to mention, keeping the ability to manufacture military helicopters alive in two rather than one organisation (accepting that each involves multiple players). The SB1 looks like a much better replacement for the Apache than the V280, but on the other hand, the V280 looks very good as a Blackhawk replacement...
I think most serious engineers would tell you that no single configuration is best all all missions ranging from light scout to ultra-heavy lift. A mix of ABC, tilt rotors, and yes, even conventional helicopters is what will best meet the USG performance vs. cost goals for each mission need.
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Old 9th Oct 2017, 15:59   #84 (permalink)
 
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Originally Posted by riff_raff View Post
Good point about the AW609. Looking at the picture below shows that area of the AW609 to be fairly well protected from impacts with the nacelle tilted vertical.
"Well protected" perhaps from prying eyes only. In the event of a birdstrike, the thin fiberglass nacelle fairings might well as be made of a wet paper bag. They will do nothing to attenuate the energy.
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Old 9th Oct 2017, 16:47   #85 (permalink)
 
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Originally Posted by SansAnhedral View Post
"Well protected" perhaps from prying eyes only. In the event of a birdstrike, the thin fiberglass nacelle fairings might well as be made of a wet paper bag. They will do nothing to attenuate the energy.
You hope they’re either stiff enough to deflect the bird (not likely unless a glancing blow) or the bird punches a hole through the fairing... one of the worst cases is if a fairing deflects like cloth as the bird penetrates the structure and helps contain the mass of the bird as it strikes real structure inside. Better to have the bird uncontained and allowed to 'flow' around structure like rods and struts. Of course, the impacted structure still has to be strong enough to survive those events. Bird strike testing and analysis was one of the more interesting problems I’ve dealt with.
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